The present invention generally relates to a bone plate having a screw blocking mechanism. More particularly, the present invention relates to a cervical bone plate having a screw blocking mechanism that can be actuated by a tool.
Bone plates and bone screws are often used in orthopedic applications. For instance, bone plates and bone screws are used in connection with the stabilization or fusion of vertebral bodies in the spine, and are also used in connection with trauma applications, for instance, in fracture fixation. In many instances, there is concern that bone screws may loosen after implantation of a bone plate. To the extent that this occurs, it has been desirable to ensure that the screw does not fully remove itself from the bone and bone plate. Many plate systems include means for affirmatively locking the bone screw upon implantation through the plate. In other instances, a blocking mechanism is employed.
A blocking mechanism does not affirmatively hold the screw in its implanted position upon implantation or lock the bone screw to the plate; rather, it merely serves to block an already loosening screw from backing out any further from the plate.
Screw blocking mechanisms which are associated with the plate prior to insertion of a bone screw are known. In some instances, such blocking mechanisms allow for the insertion of the bone screw via the resiliency of the blocker itself. For example, a split ring may be housed in a recess in a bone screw receiving hall, such as that shown in U.S. Pat. No. 6,602,255.
It may be desirable to prevent expansion of a blocker after a bone screw and bone plate have been implanted. The present invention addresses this desirability.